Preparation of protocatechuic aldehyde



15 nitrated hydrocarbon heretofore used as a solvent of procedure is as follows:

Patented Jan. 7, 1936 UNITED STATES PATENT OFFICE PREPARATION OF PROTOCATECHUIC ALDEHYDE Marion Scott Carpenter, Nutley, and Eric C.

Kunz, Montclair, N. J assignol's to Givaudan- Delawanna, Inc., New York, N. Y}, a corporation of New York 1 No Drawing. Application May 26, 1984,

, Serial No. 727,728

6 Claims. (01. 260-137) This invention relates to preparation of prototropine may be split with an almost quantitative catechuic aldehyde, and has for its objects to pro-' yield of protocatechuic aldehyde if an amount of 'Vid a process wherein a maximum yie d is obaromatic hydrocarbon (such as toluol) only half tained with a minimum of tar and by-products, sufficient to combine with the methylene chloride I and also by employing an aliphatic chlorinated according to the above equation be used, instead y bo Solvent to enable recovery thereof of the large excess cited in the patent referred to. without contamination and without substantial Thus, while the reaction proceeds in the manloss. ner specified above when working according to the D. R..P. 591,888 discloses the preparation of specifications of the patent previously cited, our

10 protocatechuic aldehyde by the reaction of an reaction is conducted in a manner essentially dif- 1o hydrous aluminum chloride upon heliotropine in ferent' and much simpler, as will be described the presence of an aromatic hydrocarbon and hereinafter. an aromatic nitrated' hydrocarbon. Without intending to restrict ourselves to the We have now discovered that the aromatic exact proportions-mentioned, the general method in the reaction, may be replaced to great advantage by ethylene dichloride, methylene dichloride, i i V chloroform, carbon tetrachloride or similar chlo- To one molecular equivalent of heliotropine disrinated hydrocarbons. This discovery was not. solved in a' solvent such as ethylene dichloride is to be foreseen, inasmuch as these chlorinated added. two molecular equivalents of anhydrous 20 products would be expected to react with the aluminum chloride. One equivalent dissolveswith aromatic hydrocarbfln o produce hydrocarbons evolution of:.heat and the other remains in sus- Of the tri-lJhenyl methane yp Su pension. When the solution is complete one densations do not take place, however, in the equivalent of toluol (or similar hydrocarbon) is 1: presence of heliotropine, and the solvent is recovadded and the temperature raised to 40. Stir- 25 ered unchanged. I ring is maintained at.409-50 until the reaction The summation of the reaction can be expressed i fco'mplete, as evidenced by-the cessation of hyby the following equations: drogen chloride evolution. The reaction mixture CH0 CH0 is decomposed in the customary manner by pouring onto ice and. hydrochloric acid. 0

, At this stage one of the advantages of our v process becomes apparent. The protocatechuic o +2A10lr o-Alol, +clon,ol aldehyde, being insoluble both in ethylene dichloride and in the aqueous solution of aluminum o-on, Al0h salts, separates out as a sludge.

- The whole is filtered and the aldehyde thus obtained, which constitutes the major portion of the total yield is washed on the filter with fresh ethylene dichloride. After drying it is obtained substantially pure, the only contamination being traces of aluminum hydrate. The small portion A101 H of the aldehyde which remains dissolved in the aqueous solution may be extracted with a suitable In D. R. P. 591,888 it was assumed that the Solvent Such as ether methylene chloride firmed by the Splitting 01 the The ethylene dichloride is recovered without 45 methylene dioxy bridge then reacted with the loss and free from toluolby distillation of the math? hydrocarbon (for example {7011101) to form non-aqueous filtrate. The toluol-methylene diditolyl methane: i chloride condensation product remains behind as OH: CH; CH; 7 a tarry residue. The fact that the solvent is recovered uncontaminated constitutes a further ad- 50 vantage over the use of mixed solvents, because f "5 +2HC1 in the latter case an indeterminate amount of one 011,- i p is used and the recovered solvent seldom has a r constant composition. We have made the further discovery that helio- The following is a specific example of the'prac- 55 Example 1 CH0 CH0 tice of our invention, it being understood that the ethylene dichloride may be replaced by carbon tetrachloride, chloroform, methylene dichloride, tetrachlor ethane or similar chlorinated hydrocarbons of the aliphaticseries; that the toluol maybe replaced with equal effectiveness by benzol, xylol or other aromatic hydrocarbons; and that the proportions cited may be varied within reasonable limits, except that at least two molecular equivalents of aluminum chloride should be used for one molecular equivalent :of heliotropine for best yields.

Example 2 150 grams heliotropine is dissolved in 800 grams ethylene dichloride and cooled to about 5 C. 266 grams aluminum chloride is added at such a rate as to keep the temperature at 5-10", cooling if necessary. 92 grams toluol is then added and the temperature raised rapidly to about 35 at which point a steady evolution of hydrogen chloride commences. Stirring is :maintained at a temperature of 35 .to 50-until th'e gas :evolution has ceased. The reaction mixture is poured, while still warm, intoiice iand hydrochloric acid and stirred thoroughly. The resulting pasty mass is filtered directlyrand the :crystals washed with freshethylene dichloride. 117 grams is thus obtained. Extraction of the aqueous 'filtrate yields a further 14 grams. The :protocatechuic aldehyde thusobtained 1312grams-represents a yield of 95% of the theory. Without further purification 'it "shows annltingpoint of 5148.

'The invention claimed .is:

1. Process for the manufacture of 'protocatechuic aldehyde comprising .reacting heliotropine with anhydrous aluminum chloride in the presence of an aliphatic chlorinatedhydrocarbon solvent, fo'llowed by "treatment with :an :aromatic hydrocarbon, said rheliotropine being present in amount tsuflicient to prevent t-reaction between said solvent and "said aromatic hydrocarbon.

2. Process for the manufacture "of protocatechuic aldehyde comprisingrdissolvin'g heliotropine in :an aliphatic chlorinated hydrocarbon, adding anhydrous aluminumchloride .while maintaining a lowered temperature, adding :an aromatic hy- 'while maintaining a lowered temperature, adding an aromatic hydrocarbon while maintaining 'sufiicientheliotropine in the solution to prevent reaction between said solvent and said aromatic hydrocarbon, raising the temperature, and 15 recovering. the aldehyde.

4'. Process for the manufacture of protocatechuic aldehyde comprising dissolving heliotropine in an aliphatic chlorinated hydrocarbon, adding anhydrous aluminum chloride while maintaining a lowered temperature, adding an aromatic hydrocarbon in an amount equimolecular to the heliotropine, raising the temperature, and recovering the aldehyde.

5. Process for the manufacture of protocatechuic aldehyde comprising dissolving one molecular amount of heliotropine in an aliphatic chlorinated hydrocarbon, adding at least two molecular amounts of anhydrous aluminum chloride while maintaining a lowered temperature, adding an aromatic hydrocarbon in an amount equimolecular to the heliotropine, raising the temperature, .and recovering the aldehyde.

'6. Process for the manufacture of protocatechuic aldehyde comprising dissolving heliotropine in an aliphatic chlorinated hydrocarbon, adding anhydrous aluminum chloride while maintaining a lowered temperature, adding an aromatic hydrocarbon and raising the temperature while maintaining tsufficient heliotropine in the solu- 4'o "tion to prevent reaction between said solvent and said aromatic hydrocarbon, and separately recovering the aldehyde and the chlorinated hydrocarbon.

MARION SCOTT CARPENTER. ERIC C. KUNZ. 

